Dr. Wensel's research has focused on structure and function of membrane-associated multimeric protein complexes that mediate visual signal transduction. These include a G protein-regulated cGMP phosphodiesterase (PDE), the visual G protein, transducin (Gt), their complexes with one another, and a cGMP-gated cation channel. Dr. Malinski has imaged the PDE in ice both without membranes and adhering to the surface of phospholipid vesicles, and is subjecting it to single-particle analysis. Small crystalline domains of PDE and somewhat larger ordered lattices of transducin have been formed and imaged on the surface of phospholipid monolayers. Methods have been developed for attachment of 14 _ gold clusters to a specific subunit on PDE while retaining activity, and studies begun on optimizing conditions for imaging gold-labeled proteins. Work is continuing on obtaining better crystals, and on combining single-particle analysis and site-specific labeling to obtain a three-dimensional map of functional domains within PDE. Work has also begun on the cGMP-gated cation channel, which has now been imaged in negative stain and in ice after affinity purification, and both before and after reconstitution into phospholipid vesicles.